(With a combination of identity theft, false accusation and other tricks, it may be possible to get anyone blacklisted. Ruin their career for a few years, while they get investigated to death. If you cover your tracks properly, it can never be traced back to you. I understand this happened a lot in the United States during the McCarthy years.)

Michael Froomkin points out an interesting twist to the Juan Carlos Merida case. As part of his campaign to restore his good name, Merida was persuaded to provide confidential information on fellow students. (In a police state, this process is known as denunciation.) From one perspective, Merida's willingness to do this demonstrates that he is trustworthy; from another perspective it demonstrates the exact opposite. (Veiled Chameleon makes this comment on Michael's blog.) Meanwhile, Merida's good name remains unrestored.

The only way for the people to fight against a police state is by collective action. If everyone is on the watch list, then it ceases to be of any significance. But to deliberately get yourself onto the blacklist? Foolhardy unless everyone else does the same thing. Complex trust issues here.